(a) Technical Field
The present invention relates to an apparatus for measuring a shearing force upon sitting. More particularly, the present invention relates to an apparatus for measuring a shearing force upon sitting, which can measure a shearing force generated upon sitting.
(b) Background Art
Recently, the performance and comfort level of vehicles are being significantly improved due to the remarkable advancement of various engineering technologies. In particular, there is a large amount of interest surrounding the comfort level of seats in a vehicle, given that individuals spend a significant portion of their day in their vehicle.
Overtime seats in automobiles have evolved into different styles and forms due to demands that are a result of culture, trends, and differing body physiologies. Accordingly, a great deal of research has been conducted on the comfort level of seats in vehicles to meet these demands in different countries.
Since there are a plethora of body types that can be expected to use any one vehicle, automobile seats are designed to receive a wide range of body sizes and shapes and are typically configured to protect a driver and a passenger from vibrations and shocks from the road.
Academic studies concentrated around anatomy, behavioral science, biomechanics, and physiology are all combined in order to design seats that meet the demands of consumers. The development on automobile seats has become one of the main research projects of most automobile manufactures, and this research is generally divided into two genres. One is a study of a position of a vehicle or anthropometrical requirements associated with the seats, and the other is a study of the comfort level of an automobile seat.
For example, when sitting on an office chair and an automobile seat, the degree of comfort or discomfort is mostly determined by the quality of the material of the seat and/or the sitting posture. Since muscle fatigue and load applied to the lumbar vary according to the condition of the seat, the muscle fatigue and the load applied to the lumbar needs to be sufficiently considered in order to develop a seat of high degree of comfort.
As a part of methods of evaluating the comfort level of an automobile seat, an Automotive Performance, Execution and Layout (APEAL) survey, a survey of subjects and an uncomfortableness evaluation on contact parts through a pressure distribution of a seat cushion are typically conducted. However, even though the performance and comfort level of automobile seats in general has increased. These surveys still show that the level of comfort is not what one skilled in the art would refer to as excellent.
In other words, according to the APEAL survey, the evaluation results on the level of comfort of automobile seats shows that seats of small-sized and mid- or small-sized vehicles are at a lower to middle level of comfort, and seats of mid-sized and mid- or full-sized vehicles are at an upper to middle level of comfort currently.
Also, according to the survey from subjects and the uncomfortableness evaluation on contact parts through the pressure distribution of the seat cushion, since lumbar uncomfortableness and muscle fatigue are impossible to measure using any of the existing methods offered to automobile manufactures, a quantitative evaluation on the pressure exerted on the waist region of an individual is considerably affected by that particular individuals sitting posture and thus tests results are high erratic and unpredictable.
Some methods have been developed for measuring a pressure distribution of the seat cushion. However, these methods only consider the load that is perpendicular to the vertebral body. Furthermore, the uncomfortableness of seats is also affected by a shearing force (force that acts on a specific plane in a tangential direction, which is one of mechanical stimuli applied to a human body upon sitting) generated upon sitting in addition to the vertical load. Accordingly, a more intricate evaluation method is needed.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.